1. Field of the Invention
The present invention relates to a furnace tube for use in a semiconductor process, and more particularly, to a furnace tube with self-heating plug to eliminate condensed water in the tube.
2. Description of the Prior Art
Silicon oxide layer growing is an essential processing step in semiconductor device fabrication, and is generally performed through a thermal oxidation process in a furnace tube. FIG. 1 shows a cross-sectional view of a conventional furnace tube 100, which generally includes a gas injector 120, a thermocouple 220, a heater 240, and an opening 180 with a hollow cap 200 inserted therein. After a wet oxidation process, some over-saturated water is usually condensed on the surface around the opening 180 and the cap 200. In a later round of using the furnace, the condensed water drop will diffuse into the main body of the tube, forming an unwanted thin wet oxide layer on the silicon water surface. According to the foregoing reasons, there is a need for a furnace tube to eliminate or prevent the aforementioned water-condensing problem.